[bug]: don't use subset to check if interval vector is in the interior of the other

[lucaferranti]

Bug description

Verified floating point algorithms (such as epsilon inflation) need to check that a vector is in the interior of the other. Currently, this is done by all(x .⊂ y), but that checks it is a proper subset.

Minimum (non-)working example

Expected behavior

use all(isinterior.(x, y)) instead.

Version info

• IntervalLinearAlgebra.jl version: 0.1.1
• System information:

Julia Version 1.6.1
Commit 6aaedecc44 (2021-04-23 05:59 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, skylake)
Environment:
  JULIA_EDITOR = code.cmd -g

Related issues

See related issue in IntervalArithmetic.jl here

Additional information

Add any other useful information

[lucaferranti]

for the verified eigenvalues this requires a PR in IA as currently isinterior is not defined for complex intervals.

julia> a = (1..2) + (2..3)*im
[1, 2] + [2, 3]im

julia> isinterior(a, a)
ERROR: MethodError: no method matching isinterior(::Complex{Interval{Float64}}, ::Complex{Interval{Float64}})
Stacktrace:
 [1] top-level scope
   @ REPL[9]:1

[lucaferranti]

opened JuliaIntervals/IntervalArithmetic.jl#492